• Journal of Korean Elementary Science Education
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• v.42 no.1
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• pp.109-126
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• 2023

In this study, I took the evidence-explanation (E-E) continuum perspective to examine the epistemological implications of scientific reasoning cases designed by preservice elementary teachers during their simulation teaching. The participants were four preservice teachers who conducted simulation instruction on the seasons and high/low air pressure and wind. The selected discourse episodes, which included cases of inductive, deductive, or abductive reasoning, were analyzed for their epistemological implications-specifically, the role played by the reasoning cases in the E-E continuum. The two preservice teachers conducting seasons classes used hypothetical-deductive reasoning when they identified evidence by comparing student-group data and tested a hypothesis by comparing the evidence with the hypothetical statement. However, they did not adopt explicit reasoning for creating the hypothesis or constructing a model from the evidence. The two preservice teachers conducting air pressure and wind classes applied inductive reasoning to find evidence by summarizing the student-group data and adopted linear logic-structured deductive reasoning to construct the final explanation. In teaching similar topics, the preservice teachers showed similar epistemic processes in their scientific reasoning cases. However, the epistemological implications of the instruction were not similar in terms of the E-E continuum. In addition, except in one case, the teachers were neither good at abductive reasoning for creating a hypothesis or an explanatory model, nor good at using reasoning to construct a model from the evidence. The E-E continuum helps in examining the epistemological implications of scientific reasoning and can be an alternative way of transmitting scientific reasoning.

• Journal of Korean Elementary Science Education
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• v.37 no.2
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• pp.173-187
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• 2018

The purpose of this study is to clarify the specific terms of epistemic and epistemological by reviewing the literature on epistemological understanding of science learning, examine the necessity of epistemic discourse analysis based on the view of social epistemology, and provide an exemplar of practical epistemology analysis for elementary children's science learning. The review was conducted in terms of meaning and terminology about epistemic or epistemological approach to science learning, epistemology of/for science, and methodologies for epistemic discourse analysis. As an alternative way of epistemic discourse analysis in science classroom I employed practical epistemology analysis (by Wickman), evidence-explanation continuum (by Duschl), and DREEC diagram (by Maeng et al.). The methods were administered to an elementary science class for the third grade where children observed sedimentary rocks. Through the outcomes of analysis I sought to understand the processes how children collected data by observation, identified evidence, and constructed explanations about rocks. During the process of practical epistemology analysis the cases of four categories, such as encounter, stand-fast, gap, and relation, were identified. The sequence of encounter, stand fast, gap, and relation showed how children observed sedimentary rocks and how they came to learn the difference among the rocks. The epistemic features of children's observation discourse, although different from scientists' discourses during their own practices, showed data-only conversation, evidence-driven conversation, or explanation inducing conversation. Thus I argue even elementary children are able to construct their own knowledge and their epistemic practices are productive.

• Journal of The Korean Association For Science Education
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• v.33 no.4
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• pp.840-862
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• 2013

This study undertook a methodological investigation on previous research that had proposed alternative methods for analyzing argumentative discourse in science classes in terms of collaborative construction and epistemic enactments of argumentation. The study also proposed a new way of analyzing argumentation discourse based on the achievements and limitations of previous research. The new method was applied to actual argumentation discourse episodes to examine its feasibility. For these purposes, we chose the studies employing Toulmin's argument layout, seeking for a method to analyze comprehensively the structure, content, and justification of arguments, or emphasizing evidence-based reasoning processes of argumentation discourse. In addition, we contrived an alternative method of analyzing argumentative discourse, Discourse Register on the Evidence-Explanation Continuum (DREEC), and applied DREEC to an argumentative discourse episode that occurred in an actual science classroom. The advanced methods of analyzing argumentative discourse used in previous research usually examined argument structure by the presence and absence of the elements of Toulmin's argument layout or its extension. Those methods, however, had some problems in describing and comparing the quality of argumentation based on the justification and epistemic enactments of the arguments, while they could analyze and compare argumentative discourse quantitatively. Also, those methods had limitations on showing participants' collaborative construction during the argumentative discourse. In contrast, DREEC could describe collaborative construction through the relationships between THEMEs and RHEMEs and the links of data, evidence, pattern, and explanation in the discourse, as well as the justification of arguments based on the flow of epistemic enactments of the argumentative discourse.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.265-270
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• 2012

Many observations have found evidence of the presence of a large number of heavily obscured Active Galactic Nuclei (AGNs). However, the nature of this population is only poorly understood because heavy obscuration by dust prevents one from finding them at optical wavelengths. Mid-infrared AGN searches can overcome this obstacle by penetrating through dust and by detecting direct emission from the dust torus. Thus, we can identify most of the AGN population, including type-2 and buried AGNs. Using the AKARI mid-infrared all-sky survey, we performed an AGN search in the nearby universe. Utilizing the 2MASS photometry, we selected mid-infrared-excess sources and carried out near-infrared spectroscopic observations in the AKARI Phase 3. During these follow-up observations, we have found three galaxies that show strong near-infrared red continuum from hot dust with a temperature of about 500 K, but do not show any AGN features in other wavelengths. The most suitable explanation of near-infrared continuum is the presence of central AGNs. Therefore, we conclude that they are AGNs obscured by dust. We performed X-ray observations of the two galaxies with SUZAKU. No detections in the 0.4-10 keV suggest that the column density may be much higher than $N_H=10^{23.5}cm^{-2}$. Comparing the masses of the host galaxies with those of the SDSS AGNs, we find that the host galaxies of the dusty AGNs discovered with AKARI are less massive populations than those of optically selected AGNs.